A hybrid electric vehicle is a vehicle using two or more power sources and uses an engine and a motor as power sources in general. The hybrid electric vehicle can be achieved in various layouts according to arrangements of the engine and the motor.
One type of arrangements of an engine and a motor in the hybrid electric vehicle is TMED (Transmission Mounted Electric Device) type. According to the TMED type, the engine, the motor and a transmission are connected on a drive shaft in series.
An engine clutch is disposed between the engine and the motor. The hybrid electric vehicle can be operated at an electric vehicle (EV) mode or a hybrid electric vehicle (HEV) mode depending on engagement and disengagement of the engine clutch.
The vehicle travels only with driving torque of the motor at EV mode and travels with driving torque of the motor and the engine at HEV mode, and the EV mode and the HEV mode are achieved by engagement and disengagement of the engine clutch.
Recently, use of hybrid electric vehicles or plug-in hybrid electric vehicles is increasing, and demand for expanding a region where the hybrid electric vehicles or the plug-in hybrid electric vehicles can travel in the EV mode is also increasing to reduce fuel consumption.
In order to expanding the region where the hybrid electric vehicle travels in the EV mode, it is necessary to increase capacity of the motor provided in the hybrid electric vehicle. Accordingly, it has been researched to increase capacity of the motor in a TMED system or to use two or more motors.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.